Poster vienne ecr
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This study assessed the feasibility of reducing radiation exposure during coronary CT angiography (CCTA) using only modified acquisition parameters on a 64-slice CT scanner. Over 85% of patients were able to undergo prospective CCTA, which significantly reduced radiation dose compared to historical levels and conventional angiography. Image quality remained high, with over 97% of coronary segments evaluated as having either excellent, good, or fair quality. The study demonstrated that very low dose CCTA is possible using standard equipment by optimizing acquisition settings.
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Poster vienne ecr
- 1. In vivo reduction of radiation exposure with a single-source coronary CT angiography effects of optimal parameters settings in real life conditions Alain Tavildari MD; François Vochelet MD; Luc Maillard MD PhD Clinique AXIUM – Aix en Provence - FRANCE
- 3. BACKGROUND Coronary computed tomographic angiography (CCTA) has become a common diagnostic test for evaluating patients with coronary artery disease Radiation exposure has been deemed too high
- 4. OBJECTIVES To assess the feasibility of in vivo radiation reduction only by modifying acquisition parameters in real life conditions with a single source 64-slice CT Comparison of radiation exposure with conventional angiography
- 5. METHOD Patients : Over 18 YO Co-morbidities including diabetes mellitus and overweight were not excluded Coronary calcifications were not excluded All patients recieved sublingual nitrate Target heart rate was under 65 bpm at acquisition time Atenolol intraveinously was given if needed Informed consent was obtained for all patients
- 6. METHOD Acquisition parameters : General Electric VCT Xte Prospective acquisition if heart rate (HR) under 65 bpm 80 kV or 100 kV 120 mA to 400 mA Acquisition at 75% of R-R intervall No padding Retrospective acquisition if HR between 65 and 75 bpm 80 kV or 100 kV Modulation limited to 400 mA (maximum around phase 75%) Reconstruction every 10% from phase 0% to phase 90%
- 7. METHOD Image quality : Evaluatued on a per-segment basis using the American Heart Association coronary model Two independant observers gradded image quality on a 4 point scale 1 : excellent : vessel fully evaluable, no artifact 2 : good : vessel fully evaluable, slight artifacts 3 : fair : evaluable concerning the presence of stenosis, blurred vessel margins 4 : unevaluable Average quotation was taken into account if in case of difference between the 2 observers
- 8. METHOD Radiation dose Based on the dose-lenght product (DLP, mGy.cm), and effective dose (ED, mSv) ED derived from DLP using a conversion factor of 0.014 for male and 0.017 for female
- 9. METHOD Conventional angiography Performed for patients with coronary stenosis on CT GE Innova® all-digital X-Ray system No ventriculography Radiation dose expressed with Dose Surface Product Conversion factor for ED = 0.2
- 10. IMAGE QUALITY = 1 (excellent)
- 11. IMAGE QUALITY = 2 (good)
- 12. IMAGE QUALITY = 3 (fair)
- 13. IMAGE QUALITY = 4 (unevaluable)
- 14. RESULTS : patients characteristics (n=137)
- 15. IMAGE QUALITY Over 2055 segments 97.7 % were evaluable (quality score 1,2 or3) 86 % were good or excellent (quality score 1 or 2)
- 16. RESULTS Prospective acquisition has been performed for 85.4 % of patients (n=117) Conventional angiography done for 20 patients to confirm coronary stenosis seen on CT
- 17. RESULTS p < 0.0001 p < 0.0001
- 18. SUMMARY Our study was able to demonstrate that very low dose coronary CT is feasible with a standard 64 slice CT Radiation dose was dramatically reduced in all acquisition modes compared to historical data and to conventional angiography Prefered mode is prospective
- 19. STUDY LIMITATION Non randomized study Single center Conventional angiography not made for all patients Subjective image quality evaluation
- 20. CONCLUSION These data may reconsider the decisional algorithm for coronary artery stenosis detection Radiation dose for the whole studied population is nearly as low as a mammogram CCTA could be proposed, with the parameter settings used in this study, for screening asymptomatic patients with high cardio-vascular risk factors